1. Field of the Invention
This invention relates to novel dithiocarbamylureas which are useful as rubber curing agents.
2. Reference of Interest
U.S. Pat. No. 3,947,511, discloses compounds having the structure X(NHC(O)NRSC(S)NR.sup.1 R.sup.2).sub.n, wherein R and R.sup.1 may be the same or different and are hydrogen, alkyl, cycloalkyl, aralkyl, etc.; R.sup.2 may be alkyl, cycloalkyl, aralkyl, etc.; R.sup.1 and R.sup.2 together may be polymethylene or oxydiethylene, n may be 1 or 2, and if n equals 1, X is C.sub.1 -C.sub.8 alkyl. If n equals 2, X is alkylene, O-- or S interrupted alkylene, alkenylene, alkylenbis(arylene), arylenebis(alkylene), or aryl of up to 13 carbon atoms. A compound typical of the U.S. Pat. No. 3,947,511 is C.sub.2 H.sub.5 NCH(O)NHSC(S)--N(CH.sub.3).sub.2.
It has been found that the urea accelerators of the instant invention exhibit superior performance over the closest known prior art.
Compounds of the instant invention may be employed as rubber curatives, usually in combination with sulfur and optionally with other rubber curing agents such as mercaptobenzothiazole disulfide, N,N-oxydiethylenebenzothiazolesulfenamide and the like. Rubbers which can be cured with the instant compounds include natural rubber, cis- or trans-polyisoprene, polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, ethylene-propylene-non-conjugated diene terpolymer and the like.